LAUSR

This paper aims, using classic hydrogeologic techniques, Time Series Analysis, Principal Component Analysis, Standardized Precipitation Index, and MRC methods to better understand the hydrogeological, and hydraulic characteristics of a mature karst aquifer system, and to analyze its behavior under drought conditions. The study area is the karst aquifer system of Aggitis (AAS), Northern East Greece, characterized by a mountainous terrain consisting of highly fissured and karstified Falakro marbles of Mesozoic age. AAS catchment extends 63.4 km2 and exhibits a duality of conduit and/or diffuse flow model. AAS is drained by the permanent large Maaras spring with a mean annual value of 4.656 m3/s. The dominant chemical type is Ca-HCO3. PCA and hydrochemical analysis were effectively used in combination to interpret the main hydrogeochemical mechanisms controlling karst water quality. A combined methodology provides a useful and effective tool for assessing the characteristic behavior of karst springs under drought conditions. It enables also, to gain insight into the prevailing processes in a karst aquifer system. The statistical analysis of hydrological data revealed the karst system is mainly recharged by diffuse infiltration.